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L1SRAKY 
STATE ^ANT BOARD 



E-855 



United States Department of Agriculture 

Agricultural Research Administration 

Bureau of Entomology and Plant Quarantine 



EVALUATION OF FUMIGANTS FOR SHELLED CORN" 



1/ 



By L. M. Redlinger, B. R. Wilson,-' R. T. Cotton, and H. H. Walkden 
Division of Stored Product Insect Investigations 



The Government grain-loan program authorized by the Agricultural 
Adjustment Act of 1938 led to the holding of large quantities of shelled 
corn in farm-type storage structures. At first conventional round gal- 
vanized-metal bins were used mostly, but later many types of wooden 
and metal bins, quonsets, and warehouses came into use. 

When the bins were new, the only insects found in them were species 
that had been carried in with insufficiently cleaned corn or that had 
reached the bins by flight. Infestations found during the first few years 
consisted almost entirely of grain beetles, the immature stages of which 
are free living. Recently, however, there has been an increase in 
weevils, the grubs of which feed inside the corn kernels. In some States 
more than one-third of the bins contain weevil infestations. This change 
in the insect population with its increase of forms more resistant to 
fumigants, together with the new types of storage structures, has neces- 
sitated continued research to develop more effective fumigants and 
dosages. 

Early in the program a 75-25 mixture of ethylene dichloride and 
carbon tetrachloride was adopted as the standard fumigant for shelled 
corn in steel bins for application at a dosage of 6 gallons per 1,000 
bushels. Later an 80-20 mixture of carbon tetrachloride and carbon 
disulfide at 5 gallons per 1,000 bushels came into favor and largely 
replaced the one containing ethylene dichloride. 

Many failures were reported with these fumigants, but usually they 
could be accounted for by the presence of excessive amounts of caked 
and damp grain on the surface or throughout the bin and also by the 
large amounts of dockage. Occasionally incomplete kills appeared to 
be associated with outbreaks of the Angoumois grain moth. 

Some of the tests made with old and new fumigants under varying 
conditions and in various types of structures are reported herein. 



1/ A portion of the tests reported herein were made in cooperation 
with the Grain Branch of the Production and Marketing Administration. 

2/ Resigned April 13, 1951. 



.-..-its and 

:• :. .. J' 

nat the full I ant 

luadra 

, 

bin. In some tests an ad aJ sample was 

tak ampb 

ill free-living forms, and tl held for possible 

• of weevils ths. The living and dead ins* 

avera tsis of a 1,000-gram samp 

Tests with 80-20 Mixti. 

The 80-20 mixture of carbon tetrachloride and carbon disulfide 
i.'d under many conditions and in all types of storage structures. In 
:ieral, a dos. 5 gallons per 1,000 bus* found to be adequate 

•he treatment of clean, dry, sheik- '-el 

bins and for the spot treatment of isolated infestations in quonsets or 
similar lar ge storage structures. I "h mu 

th( surface or large ami *age and caked corn through- 

out the bin, this ige was inadequ. Before fu on it was n« 

essary to remove all caked and mo. surface and turn 

and i rider of the bin. 

In wooden rectangular bins o , drj rn, a dosa* Ions 

1,000 bushels was founc isa ive results. 

ta with I 

and in a mixture with other ran 
bins of shell n, i he corn a 

irfac( is hot, 

vith bi ties. In prepi >r fun 

■ 
CI rinkli ; a 

wa ! m JU1 al 

■ 



-3 - 



of chloropicrin in 1 gallon of (1) carbon tetrachloride, (2) the 80-20 
mixture of carbon tetrachloride and carbon disulfide, or (3) the 75-25 
mixture of ethylene dichloride and carbon tetrachloride. All mixtures 
were sprayed over the surface of the grain. 

Chloropicrin in admixture with carbon tetrachloride was tested at 
dosages of 1, 1 l/2, and 2 gallons per 1,000 bushels. The results were 
much better than with the chloropicrin alone, but even with the 2-gallon 
dosage a complete kill was not obtained. 

Chloropicrin with the 80-20 mixture in dosages up to 1 1/2 gallons 
and with the 75-25 mixture in dosages up to 2 gallons per 1,000 bushels 
failed to give complete kills. 

The results of these tests are given in table 1. In the first three 
treatments with chloropicrin alone and the first two with the chloropicrin- 
carbon tetrachloride mixture, the average number of insects per 1,000- 
gram sample was computed from two bins. All the other averages are 
on the basis of one bin only. 

Table 1. --Effectiveness of chloropicrin and chloropicrin mixtures in the 
fumigation of shelled corn in steel bins, 1950 



Fumigant 



Dosage 

per 1,000 

bushels 



Temper- 
ature of 
corn(°F.) 



Average number of 
insects per 1,000- 
gram sample 



Alive 



Dead 



Chloropicrin alone 



Chloropicrin 2 lb. in 1 gal. of- 
Carbon tetrachloride 



80-20 mixture 



75-25 mixture 



Pounds 








2 


96 


37 


9 


2 1/2 


94 


17 


21 


3 


96 


10 


20 




96 


95 


66 




73 


114 


22 


4 


100 


127 


55 


Gallons 








1 


85 


7 


8 


1 1/2 


90 


3 


9 




68 


77 


95 




80 


55 


99 


2 


88 


6 


126 




92 


6 


60 


1 1/4 


78 


6 


130 


1 1/2 


79 


215 


71 


1 1/2 


96 


165 


79 


1 3/4 


97 


68 


35 


2 


96 


107 


59 



i - 

Mixture 

I fumigai 

• 
9 of the standard 80-20 and 
nail quantities of a more toxic n. 
>f methyl bron ts 

>f these- mixtures. In the first tests with the 
•it of sulfur dioxide was also added as a warning gas. 

,200-bushel metal bins of shellec: 

>or eondr 
r of damp, d mol 

grain at th< Air temperatures ranged from 50° to . and 

50° to 9 
for the fun n the caked surface gra -n 

with shovels. Three replications of both mixtu; -*re mad« 

•id 3 gallons per 1,000 bushels. <> fumigant was applied 

ov surfa* ijrain with a pump that delivered 2 gallons p- 

Q. 
>ken 1 week after fun in sho it a n< om- 

kill ha led in all bii th both mixtures th dosages. 

In three of the twelve bins a single live insect was found in ice 

. in. 

ts, undertaken in wa fumigai ted 

that some i aked gra. 

lin was removed befoi 

this troul ne (table 

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k had shown m n admixtur. 

nide or chl< in to be promising for the fumigation 

: metal bins. Such mixtures B .e 

under pressure in cylinders that Lf- emptying, Tiat th> 

applied from outside the bin by merely opening a valve and allowing 
fumigant to flow through a tube into the grain. 

ill tests with these mixtures a coil of plastic tubing i to 

the cylinder was buried 6 to 8 inches 1 th the surface of the grain. 

Th«- tubing extended in a complete circle about 2 feet from the walls of 
n with the free end across the middle. I was plugged and 

holes were bored through the tubing at 3-foot intervals. By placing the 
cylinder of fumigant on a pair of scales it was possible to weigh in tl 
iired amount of fumigant. The mixtures caused frequent breakages 

in the tubing. 

Mixtures containing methyl bromide and ethylene dibromide were 
made in the following proportions by volume: 1-1, md 1 

All mixtures were used at the rates of 5, and 7 1/2 pounce 

1,000 bushels. 

n treated was in poor condition- -heavily Infe 
in spots. Grain temperature.- nerally high ar; 

101 • tures 7 4° to 82° and grail 

ent. Cal 
tion. 
■ 

, althougl 
[n n 



- 7 - 



air temperature at the time of fumigation was 75°. Dosages of 3, 5, 
and 7 pounds of this mixture were applied in the same manner as the 
methyl bromide-ethylene dibromide mixtures. Practically no kill of 
adult insects was obtained at any dosage (table 2), although there was 
little emergence of weevils from samples of grain removed after treat- 
ment. 

Ethylene Dibromide-Ethylene Dichloride- 
Carbon Tetrachloride Mixtures 

A mixture containing 7.2 percent of ethylene dibromide, 29.2 percent 
of ethylene dichloride, and 63.6 percent of carbon tetrachloride (by 
weight), known as EB-5 grain fumigant, was tested in steel bins at 
dosages of 2, 3, and 5 gallons per 1,000 bushels. The fumigant was 
applied uniformly over the surface of the corn in a coarse spray. 
Probe samples taken 2 weeks after fumigation showed that an average 
of one adult insect per 1,000 grams survived fumigation at both the 2- 
and 3-gallon dosages, but that at the 5-gallon dosage mortality was 
complete. Weevils emerged from samples of grain fumigated at the 
two lower dosages, but not from samples fumigated at the 5-gallon 
dosage. 

A mixture containing 18.3 percent of ethylene dibromide, 24.1 per- 
cent of ethylene dichloride, and 57.6 percent of carbon tetrachloride was 
found to be no more efficient. 

1, 1-Dichloro-l-nitroethane-Carbon Tetrachloride Mixture 

A mixture containing 2 pounds of 1, 1 -dichloro-1-nitroethane in 1 
gallon of carbon tetrachloride (approximately 17-83 percent by volume) 
was tested at dosages of 1, 2, and 3 gallons per 1,000 bushels. The 
fumigant was applied in a coarse spray uniformly over the surface of 
eight 3,200-bushel bins. The caked and moldy surface grain was re- 
moved and the surface leveled with a rake. Grain moistures ranged 
from 10.3 to 13.7 percent, grain temperatures from 72° to 94° F., and 
the air temperature at the time of fumigation was 80°. 

A dosage of 1 gallon per 1,000 bushels did not give a complete kill 
of adult insects, but at both the 2- and 3-gallon dosages the kill was 
nearly complete (table 2). No weevils emerged from grain samples 
taken from the bins after fumigation. 

Bromotrichloromethane-Carbon Tetrachloride Mixture 

A mixture containing 10 percent of bromotrichloromethane (by 
volume) and 90 percent of carbon tetrachloride was tested at 3 and 4 
gallons per 1,000 bushels. It was applied as a coarse spray uniformly 
over the surface of the grain in 3,200-bushel metal bins. The crusted 



■ 
■ 

. 
fa« 
ad;. 

a 

nun f mat' 

■ 
in admixtui i 

I 1 gal lor 
bushel bin. d 30 ; 

in f I 

' per 1| 
a< hloi 

111 £\J I O 

tmei 

i 

hels. ( 

■ 

■ 

■ 

: ■ 



Digitized by the Internet Archive 

in 2013 



■ 

V: : ' 

http://archive.org/details/shelledfumiOOunit 



-9 



boom on a sled so that it could be pulled across the surface of the corn 
from outside of the building while the fumigant was sprayed in a pattern 
that covered the corn from one side of the building to the other (figs. 1 
and 2). 




Figure 1.-- Sled with spray boom 
mounted and connected to pump 
and supply tank. 



Figure 2. --Sled with spray boom 
on surface of corn in quonset. 



The spray boom is made of a 24-inch length of 3/4-inch gas pipe 
bearing a nozzle with two 3/4-inch off-center nozzles. It is held firmly 
to a horizontal support pipe by U-bolts and strap irons to make a pipe 
clamp. The support pipe is of 3/4-inch gas pipe fastened by I-bolts to 
the uprights of the sled, 44 inches high for quonsets 32 feet wide and 
49 inches high for those 40 feet wide. This pipe can be rotated by 
loosening the I-bolts. A hose-to-pipe fitting is attached to the front 
end of the nozzle pipe and a 90° street L to the back end. The nozzle 
is attached to the street L. The nozzle tips should be level with the 
support pipe and about 12 to 15 inches back of it, with the angle between 
the nozzles about 20° to 30°. The slotted disks in the nozzles should 
have the wide portion to the top or outside and the slots perpendicular 
or parallel to the support pipe. In this position each nozzle will cause 
the spray to cover the area from the center of the quonset to the opposite 



UBRARY 
STATE PLANT BOARD 



10 



I ■ - :" imigant I from the other end of the noz/ 

This hos«- m . nough to rea m the ba - 

;mmp or U le of tl nl of the building. 

I fitf. 1). • ut 65 pounds, is con -d 

with run: ns of an drum 

front to keep them sliding. I tie uprigh" of 2- by 2- 

A gear pun. ngatlOO [x>unds per square u. I deli. 

it 2 1/2 gallons of fumigant per minute. H • the use of a small winch 
and a wire attached to the sled, the boom spray can be drawn fn 

to the front of the quonset at a speed that will deliver the re- 
quired dosage uniformly ov< Such an outfit can be constructed 
at a nominal cost, is easily ham: .rid will fit into the b< k. 
A competent crew should be able to treat a quonset in about 30 minutes. 

D -sages of 2 1/2 and 3 gallons of the 80-20 mixture plus 10 percent 

nethyl bromide per 1,000 bushels gave very satisfactory results. 



Summary 

■ ■. 80-20 mixture of carbon I Mloride and carbon disulfide at a 

dosage of 5 gallons per 1,000 bushels has been .indard tr nt 

shelled i orn in steel bins for st i years. ' kills 

in out-of-condition corn, scarcity of materials, and the need for 
inf< garding dos: - of storage structures led 

r study of this mix 
111 metal bins the standard dosage of th< mixt.. s satis- 

fy if cal Idy sui rain was itment 

un) estations of tl tnois grain moth wei In 

wooden bins it dosac gallons per 

100 bu I: aJ I I ins in: with tl -h. it 

- kill this insect In the SUri n. Su: 

f f urn igants proved 1 d, but 

r 100 squai 
i • • 

en1 (by volume) of methyl bromi 
2 ' mixtu i tra< W 

mixtui U< hloride or pi 

ed the 1 >oin1 a 

: .Ions per 1 .000 1)1. 

helfl of tl 20 mixture ph. 

: i ,000 bushels U 

■ 

: 



- 11 



Other fumigants found to be highly effective for the treatment of 
shelled corn in metal bins were a 17-83 mixture of 1,1-dichloro-l - 
nitroethane and carbon tetrachloride at 2 gallons and a 10-90 mixture 
of bromotrichloromethane and carbon tetrachloride at 3 gallons per 
1,000 bushels. The latter mixture did not kill all immature stages of 
the rice weevil. 

Various mixtures of methyl bromide with ethylene dibromide and 
chloropicrin were unsatisfactory under the conditions of these tests. 



II I II 

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